Format

Send to

Choose Destination
J Comput Aided Mol Des. 2015 Nov;29(11):1035-43. doi: 10.1007/s10822-015-9876-x. Epub 2015 Oct 19.

Molecular simulation assisted identification of Ca(2+) binding residues in TMEM16A.

Pang CL1,2, Yuan HB1,2, Cao TG1,2, Su JG3, Chen YF1,2, Liu H1,2, Yu H1,2, Zhang HL4,5,6, Zhan Y7,8, An HL9,10, Han YB1,2.

Author information

1
Key laboratory of Molecular Biophysics, Tianjin, Hebei Province, China.
2
Institute of Biophysics, School of Sciences, Hebei University of Technology, Tianjin, China.
3
School of Sciences, Yanshan University, Qinhuangdao, China.
4
Key Laboratory of Neural and Vascular Biology, Ministry of Education, Shijiazhuang, China.
5
The Key Laboratory of Pharmacology and Toxicology for New Drug, Shijiazhuang, Hebei Province, China.
6
Department of Pharmacology, Hebei Medical University, Shijiazhuang, China.
7
Key laboratory of Molecular Biophysics, Tianjin, Hebei Province, China. zhany@hebut.edu.cn.
8
Institute of Biophysics, School of Sciences, Hebei University of Technology, Tianjin, China. zhany@hebut.edu.cn.
9
Key laboratory of Molecular Biophysics, Tianjin, Hebei Province, China. hailong_an@hebut.edu.cn.
10
Institute of Biophysics, School of Sciences, Hebei University of Technology, Tianjin, China. hailong_an@hebut.edu.cn.

Abstract

Calcium-activated chloride channels (CaCCs) play vital roles in a variety of physiological processes. Transmembrane protein 16A (TMEM16A) has been confirmed as the molecular counterpart of CaCCs which greatly pushes the molecular insights of CaCCs forward. However, the detailed mechanism of Ca(2+) binding and activating the channel is still obscure. Here, we utilized a combination of computational and electrophysiological approaches to discern the molecular mechanism by which Ca(2+) regulates the gating of TMEM16A channels. The simulation results show that the first intracellular loop serves as a Ca(2+) binding site including D439, E444 and E447. The experimental results indicate that a novel residue, E447, plays key role in Ca(2+) binding. Compared with WT TMEM16A, E447Y produces a 30-fold increase in EC50 of Ca(2+) activation and leads to a 100-fold increase in Ca(2+) concentrations that is needed to fully activate the channel. The following steered molecular dynamic (SMD) simulation data suggests that the mutations at 447 reduce the Ca(2+) dissociation energy. Our results indicated that both the electrical property and the size of the side-chain at residue 447 have significant effects on Ca(2+) dependent gating of TMEM16A.

KEYWORDS:

Calcium-binding site; Homology modeling; Molecular dynamics; Patch clamp; Site-directed mutagenesis; TMEM16A

PMID:
26481648
DOI:
10.1007/s10822-015-9876-x
[Indexed for MEDLINE]

Supplemental Content

Full text links

Icon for Springer
Loading ...
Support Center